$view->args is empty in page display, but contains the arguments in the preview of the view (and yes, I cleared the cache)

Hey people, I am having a really strange problem.

I have a view dispaying some fields (images). In the header of my view I included some php code using the php input format.
The code I put there is the following:

<?php
$view=views_get_current_view();
print_r($view->args);
print "name: ".$view->name;
print "url: ".$view->get_url();
?>

When I use the preview of the view with the argument 16, the view displays normally and the header containst the following:

Array ( [0] => 16 )
name: image_gallery
url: admin/build/views/nojs/preview/image_gallery/default/16

When I visit the view by the url of the page display though (for reference see http://kika.elcyon.nl/image_gallery/16), the view displays fine except for the header. The contents of the node is the same as in the preview of the view, the header is different though. It seems that the $view->args array is empty.
The header contains the following:

Array ( )
name: image_gallery
url: image_gallery

How this can be, I don't know, since the view displays the correct nodes/fields. The /16 in the url does get translated to an argument. But then it is somehow erased by the time the header is rendered. Neither the $view->get_url nor the $view->args contain the argument anymore. This really has me stumped.

This is my whole view, for reference:

$view = new view;

$view->name = 'image_gallery';

$view->description = 'Image gallery';

$view->tag = '';

$view->view_php = '';

$view->base_table = 'node';

$view->is_cacheable = FALSE;

$view->api_version = 2;

$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */

$handler = $view->new_display('default', 'Defaults', 'default');

$handler->override_option('relationships', array(

  'image_files' => array(

    'label' => 'Image files',

    'required' => 0,

    'image_size' => array(

      'thumbnail' => 'thumbnail',

    ),

    'id' => 'image_files',

    'table' => 'node',

    'field' => 'image_files',

    'relationship' => 'none',

  ),

));

$handler->override_option('fields', array(

  'nid' => array(

    'label' => '',

    'link_to_node' => 1,

    'which_node' => 'base_node',

    'exclude' => 0,

    'id' => 'nid',

    'table' => 'image',

    'field' => 'nid',

    'relationship' => 'none',

  ),

));

$handler->override_option('arguments', array(

  'term_node_tid_depth' => array(

    'default_action' => 'ignore',

    'style_plugin' => 'default_summary',

    'style_options' => array(),

    'wildcard' => 'all',

    'wildcard_substitution' => 'All',

    'title' => '%1',

    'default_argument_type' => 'fixed',

    'default_argument' => '',

    'validate_type' => 'taxonomy_term',

    'validate_fail' => 'not found',

    'depth' => '5',

    'break_phrase' => 1,

    'set_breadcrumb' => 0,

    'id' => 'term_node_tid_depth',

    'table' => 'node',

    'field' => 'term_node_tid_depth',

    'relationship' => 'none',

    'default_options_div_prefix' => '',

    'default_argument_user' => 0,

    'default_argument_fixed' => '',

    'default_argument_php' => '',

    'validate_argument_node_type' => array(

      'image' => 0,

      'page' => 0,

      'story' => 0,

    ),

    'validate_argument_node_access' => 0,

    'validate_argument_nid_type' => 'nid',

    'validate_argument_vocabulary' => array(

      '1' => 1,

    ),

    'validate_argument_type' => 'tids',

    'validate_argument_php' => '',

    'image_size' => array(

      '_original' => '_original',

      'thumbnail' => 'thumbnail',

      'preview' => 'preview',

    ),

  ),

));

$handler->override_option('filters', array(

  'type' => array(

    'operator' => 'in',

    'value' => array(

      'image' => 'image',

    ),

    'group' => '0',

    'exposed' => FALSE,

    'expose' => array(

      'operator' => FALSE,

      'label' => '',

    ),

    'id' => 'type',

    'table' => 'node',

    'field' => 'type',

    'relationship' => 'none',

  ),

));

$handler->override_option('access', array(

  'type' => 'none',

));

$handler->override_option('header', '<?php

$view=views_get_current_view();

print_r($view->args);

print "\\n";

print "name: ".$view->name;

print "\\n";

print "url: ".$view->get_url();

?>');

$handler->override_option('header_format', '3');

$handler->override_option('header_empty', 1);

$handler->override_option('footer', '<?php

$view=views_get_current_view();

print_r($view->args);

print "\\n";

print "name: ".$view->name;

?>

');

$handler->override_option('footer_format', '3');

$handler->override_option('footer_empty', 1);

$handler->override_option('items_per_page', 9);

$handler->override_option('use_pager', '1');

$handler->override_option('style_plugin', 'grid');

$handler->override_option('style_options', array(

  'columns' => '3',

  'alignment' => 'vertical',

));

$handler->override_option('row_options', array(

  'inline' => array(),

  'separator' => '',

));

$handler = $view->new_display('page', 'Page', 'page_1');

$handler->override_option('path', 'image_gallery');

$handler->override_option('menu', array(

  'type' => 'none',

  'title' => '',

  'weight' => 0,

  'name' => 'navigation',

));

$handler->override_option('tab_options', array(

  'type' => 'none',

  'title' => '',

  'weight' => 0,

));